Research On The Forming Die Technology Of Metallic Bipolar Plate For PEMFC

Proton exchange membrane fuel cell (PEMFC) is recognized as a new alternative to the current power sources because of its high efficiency, low emission, intensive energy and power density. However, the current cost of a fuel cell is 4-10 times as much as the cost of the internal combustion engine (PEMFC:＄200-300kw-1, internal combustion engine:＄30-50kw-1). Among the all components of the fuel cell, the bipolar plate is the largest bottleneck for the commercialization of the PEMFC, because its weight occupies 60-80% of the cell stack weight and its cost occupies 30-45% of the cell stack cost. To improve the production efficiency of the bipolar plate, reduce the cost of fuel cells and develop new technology for manufacturing fuel cell bipolar plates, forming die technology of metallic bipolar plates of PEMFC is studied, details are listed as follows:(1) Based on the comprehensive analysis of the actual research of machining process of bipolar plates of PEMFC home and abroad, especially the manufacturing method of the metallic bipolar plate was summarized. Comparing with other methods, stamping forming process was proposed as the leading way of the metallic bipolar plate forming technology with the advantages of high efficiency and good mechanical property.(2) The metallic bipolar plate with the thickness of 0.1mm was selected to study, there are 8 parallel micro-channels on its surface and its material is SS304 stainless steel. Considering the problems of sheet stamping forming, such as the wrinkle, serious thinness in the local region, crack and spring back, the stamping process of the workpiece of sheet is analyzed and the reasonable blank layout was designed, and the finite element analysis model of part was established; then critical process steps were analyzed and simulated by the finite element method using DYNAFORM, the simulated results justify the blank layout and stamping process proposed.(3) Combining with process analysis and numerical simulation, design of the blank layout, theoretical analysis and calculation, the typically die structure of metallic bipolar plate was designed and optimized. Then forming accuracy was guaranteed, the adaptability and life were enhanced with the modularized design concept, forming and reshaping process, insert and combination structure. Based on the research on the key techniques, application of advanced electron discharge machining equipments, the way to control the machining quality was analyzed, the manufacture process was monitored too. Finally, the manufacturing scheme for the key parts was optimized, which come out with the improved manufacturing process for the progressive die of metallic bipolar plate.(4) Based on the principle of Statistical Process Control (SPC), the experiment was designed for monitoring, measuring, registering, evaluating and detecting of the quality characteristics during the manufacturing process, which provides data for the mass production of metal bipolar plate.To summarize, with analysis of forming process and numerical simulation of the metal bipolar plate, the progressive die is designed in the whole level, and also the detailed structure is optimized; then the system for the analysis, simulation, design, manufacture and quality monitor for the bipolar plate of PEMFC are established, which provides a new kind of manufacturing idea and method for fabricating the metallic bipolar plate of PEMFC.